At Comic-Con International on Sunday, the 50th anniversary celebration of “Doctor Who” was all about the fans.

They came dressed up like characters from the show, and many brought props, raising their iconic sonic screwdrivers in the air and doing the show’s signature clap as cast and creators came on stage.

They came to see tons of footage of upcoming episodes and even footage honoring past “Doctors,” which had many in the audience teary-eyed.

And they came to ask questions of series stars Matt Smith and Jenna Coleman and series producer Steven Moffat, who writes the highly successful science-fiction show about a time-traveling humanoid alien. They were joined by writer/executive producer Mark Gatiss and actor David Bradley, the star of "An Adventure in Space and Time," a feature-length BBC show that will tell the story of the show's inception, back in 1963.

But one of the most important questions — who's going to replace exiting star Smith — was left unanswered.

"We haven't done that yet," he said.

Smith, who is exiting the show later this year, said the experience has "been the most fabulous journey. I’m very proud of what we’ve achieved. I take a lot of friends with me, and we’re going to try to make it the best Christmas episode … a real belter.”

In response, fans yelled: “Thank you, Matt!”

“I just wanted to say thank you for all your support and encouragement,” Smith responded, genuinely.

One fan thanked the cast for helping her through her time in the hospital fighting bone cancer as she watched the show every day.

Another asked the cast about filming in America, which they recently did. Smith said he wants to film his final episode here as well.

Moffat said he was grateful for their warm welcome when shooting in the U.S. and added that the show's creators have been surprised that the show has caught on with 20somethings in the U.S. because in the U.K., its biggest fanbase has been children and their parents.

And speaking of the U.S., Smith said American fans are definitely louder than fans in the U.K., and that they were extremely impressed by the costumes of “Doctor Who” fans at Comic-Con. He talked about how he and Coleman liked to surprise fans in San Diego by leaning out of their car windows and saying hello to fans dressed as Doctor or Clara.

With the show spanning through 50 years, one fan asked how the cast and creators would describe the Doctor, considering he’s a character who stays the same even though he's been played by different actors.

“He lives in the moment all the time. He never really looks back. He’s a creature of the moment right now,” Moffat said. “He’s all the ages at once as well. I think Matt (Smith) to date has done the best to combine the old man and the child. He doesn’t know he’s the hero.”

The show offered footage that spanned through 50 years of the show that had many fans in tears.

Moffat jumped in to talk about what it felt like to step into such a legacy and work on the show. He said it would have been a waste to be nervous of overwhelmed by the pressure.

“You feel unbelievable excited. What’s the point in feeling afraid? Even if I do it badly, it’s cool” he joked. “It’s been the a thrill and the trip of my lifetime. I still adore it and I’m still a fan.”

"The Doctor Who" 50th anniversary special will premiere Nov. 23 on BBC America.